Molecular motor works by detecting minute changes in force

July 9, 2008

Researchers at the University of Pennsylvania School of Medicine discovered that the activity of a specific family of nanometer-sized molecular motors called myosin-I is regulated by force. The motor puts tension on cellular springs that allow vibrations to be detected within the body. This finely tuned regulation has important implications for understanding a wide variety of basic cellular processes, including hearing and balance and glucose uptake in response to insulin. The findings appear in the most recent issue of Science.

"This is the first demonstration that myosin-I shows such dramatic sensitivity to tension," says senior author E. Michael Ostap, Ph.D., Associate Director, Pennsylvania Muscle Institute and Associate Professor of Physiology. "It is surprising that a molecular motor can sense such small changes in force."

Myosin-I is a biological motor that uses the chemical energy made by cells to ferry proteins within cells and to generate force, powering the movement of molecular cargos in nearly all cells.

In two specific cases, myosin I puts tension on the specialized spring-like structures in human ears that enable hearing and maintenance of balance, and also has a role in delivering the proteins that pump glucose into cells in response to insulin. "However, why a tension-sensing molecular motor is needed for this function is unknown," says Ostap.

In collaboration with Henry Shuman, PhD, Associate Professor of Physiology, the research team used optical tweezers -- a combination focused laser beam and microscope, of sorts -- to measure incredibly small forces and movements (on the piconewton and nanometer level) to discover that myosin I motors are regulated by force. The motors pull on their cellular cargos until a certain tension is attained, after which they stop moving, but will hold the tension. If something happens in the cell to decrease this tension, the motor will restart its activity and will restore the lost tension.

Myosins use the energy from ATP to generate force and motion. Humans have 40 myosin genes that sort into 12 myosin families. Members of the myosin family have been found in every type of cell researchers have examined. The Ostap lab is investigating the biochemical properties of several members of the myosin family to better understand movement in cells, which is important in development, wound healing, the immune response, and the spread of cancer, among other functions. These new findings shed light on the role of myosin I in cells, supporting the notion that this molecular motor is more important in generating and sustaining tension rather than transporting protein cargo.

The research team will now apply these results to better understand how cells use these tension sensors to carry out their physiological functions.

Related Stories

The same kind of contraction that fires our muscles also controls a key stage of mammalian embryo development, according to a new study published in Nature Cell Biology. The research, conducted at EMBL Heidelberg, measured ...

Researchers have successfully developed a realistic theoretical model that provides a rational explanation for the spontaneous oscillatory contraction (SPOC) of muscle. The findings were published in Physical Review Letters ...

During the final stage of cell division, a short-lived contractile ring constricts the cellular membrane and eventually separates the dividing cell in two. Although this "molecular muscle's" composition, mainly actin and ...

(PhysOrg.com) -- Normal vertebrate brain ventricle formation relies upon the stretchiness or "relaxation" of the neuroepithelium, which is regulated by the motor protein myosin. This process was discovered in zebrafish and ...

Every time a neuron sends a signal - to move a muscle or form a memory, for example - tiny membrane-bound compartments, called vesicles, dump neurotransmitters into the synapse between the cells. Researchers report that this ...

Recommended for you

Scientists have been making nanoparticles for more than two decades in two-dimensional sheets, three-dimensional crystals and random clusters. But they have never been able to get a sheet of nanoparticles to curve or fold ...

Serendipity has as much a place in science as in love. That's what Northeastern physicists Swastik Kar and Srinivas Sridhar found during their four-year project to modify graphene, a stronger-than-steel infinitesimally thin ...

Graphene has been called a wonder material, capable of performing great and unusual material acrobatics. Boron nitride nanotubes are no slackers in the materials realm either, and can be engineered for physical and biological ...

(Phys.org)—Currently, all light-emitting diodes (LEDs) emit light of only one color, which is predefined during fabrication. So far, tuning the color of light produced by a single LED has never been realized, despite numerous ...

When it comes to installing solar cells, labor cost and the cost of the land to house them constitute the bulk of the expense. The solar cells—made often of silicon or cadmium telluride—rarely cost more than 20 percent ...

A team of researchers from Berkeley Lab and Columbia University has passed a major milestone in molecular electronics with the creation of the world's highest-performance single-molecule diode. Working at Berkeley Lab's Molecular ...

0 comments

Please sign in to add a comment.
Registration is free, and takes less than a minute.
Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.